1. Field of the Invention
This invention relates to a magnetic transfer apparatus in which information carried by a master information carrier is magnetically transferred to a slave medium by setting the master information carrier and the slave medium in a transfer holder to bring them into close contact with each other and setting the transfer holder in a holder supporting portion of the magnetic transfer apparatus.
2. Description of the Related Art
This invention is applied to a magnetic transfer in which a master information carrier having an irregularity pattern or an embedded pattern representing information to be transferred and covered with a magnetic layer (a patterned master) is held in close contact with a slave medium having a magnetic recording area and a transfer magnetic field is applied to the master information carrier and the slave medium in this state, thereby recording a magnetization pattern corresponding to the information carried by the master information carrier on the slave medium.
When the slave medium is a disk medium such as a hard disk or a high-density flexible disk, the master information carrier is held in close contact with one or each side of the slave medium and the transfer magnetic field is applied to the slave medium and the master information carrier(s) in this state by a magnetic field application means comprising an electromagnet or a permanent magnet disposed on one or each side of the slave medium/master information carrier assembly.
In order to transfer the information in a good quality, it is important to hold the slave medium and the master information carrier in uniform close contact with each other. That is, when there is defect in close contact between the slave medium and the master information carrier, there is generated an area where no magnetic transfer occurs, which results in a signal missing in the information transferred to the slave medium and deterioration in quality of the signal transferred. When the transferred information is a servo signal, the signal missing results in an unsatisfactory tracking and deteriorates the reliability of the slave medium.
In the magnetic transfer, placing the slave medium and the master information carrier in a holder comprising a pair of holder halves which can be moved toward each other to hold the slave medium and the master information carrier in close contact with each other is advantageous in holding the slave medium and the master information carrier in close contact with each other uniformly over the entire area. See, for instance, U.S. Patent Laid-Open No. 20020030909.
A problem in the magnetic transfer is to accurately transfer the magnetization patter about the axis of rotation of the slave medium. Especially, in the case where the slave medium is a hard disk, the center of the magnetization pattern which is recorded on the slave medium by the magnetic transfer should accurately coincide with the center of rotation of the slave medium when it is rotated by a spindle motor of a disk driver. When the former center largely deviates from the latter center, the tracking function cannot be obtained. The tolerance of the primary eccentricity of the servo signal with the spindle motor kept rotated is generally about 50 to 100 μm.
The eccentricity is the sum of the errors including the eccentricity of the spindle from the center of the inner diameter of the slave medium and the eccentricity of the master information carrier and the slave medium from the axis of a holder which holds them during the magnetic transfer, and accordingly, it has been required that the eccentricity in the holder is minimized without deterioration of the processing efficiency of the magnetic transfer.
Conventionally since the holder has been fixed to the magnetic transfer apparatus body by bolts, mounting and demounting the holder on and from the magnetic transfer apparatus body is not good in workability, and adhesion to the master information carrier of dirt and/or dust generated from the operator or the parts during mounting and demounting of the holder can cause defective close contact between the slave medium and the master information carrier to deteriorate the quality of transfer.
Further since a locator mechanism for locating the holder with respect to the magnetic transfer apparatus body is not provided, the holder mounting accuracy cannot be reproduced upon change of the holders, it has been necessary to provide a fine movement X-Y stage in the holder mounting portion of the magnetic transfer apparatus body and to carry out a fine adjustment of the position of the holder each time the holders are changed.
The master information carrier held by the holder is sometimes cleaned every predetermined times of magnetic transfer to remove dust and/or dirt adhering to the surface thereof. When the master information carrier is taken out from the holder, the master information carrier must be located again in the holder after the cleaning, which is very troublesome. Accordingly, the holder is generally removed from the magnetic transfer apparatus body with the master information carrier held therein when the master information carrier is to be cleaned. Thus it is preferred that the holder be readily located with respect to the magnetic transfer apparatus body.